LAKE OF THE OZARKS, Mo. (KMOX) – It can happen in the blink of any eye and have catastrophic results — a swimmer electrocuted after coming into contact with an improperly insulated dock.

While not common, it did happen three times in Missouri within a matter of days around the 4th of July weekend last year.

An 8-year-old boy and his 13-year-old sister were killed at a dock on the Lake of the Ozarks, followed just days later by the death of 26-year-old Jennifer Lankford of Hazelwood, also at Lake of the Ozarks.

Tim Kelley with the Electrical Connection and an instructor at the Electrical Industry Training Center in St. Louis says first and foremost in preventing similar tragedies is making sure a dock has a working and properly maintained Ground Fault Circuit Interrupter, or GFCI.

“What that does is that measures the current going in and current coming out (of the water),” Kelley tells KMOX News. “And just as long as everything is following the correct pathway, everything is fine. But as soon as that electrical energy goes on a different path the GFCI is supposed to trip and disconnect all power going out to the dock.”

And that’s not the only safety measure that can be taken to ensure a fun and safe swimming season, Kelley adds.

“What would also be a good measure is making sure there’s a grounding rod,” he explains. “It’s a rod that all the metal structure on the dock is actually grounded to. That provides an easy path for electricity to go, instead of going through someone.”

Kelley says GFCI devices go for as low as $20, obviously a very small price to pay to save lives this summer.